Reducing loss in the SEC is thus one of the most critical areas of research needed to realize the high frequency sensitivity goals of Cosmic Explorer.
Since SEC loss is independent of both the tuning and the arm length [1]}, [2]}, it both reduces the sensitivity near the resonant dip and limits the frequency to which that dip can be pushed as is illustrated in fig:20kmpmquantum. The current noise estimates assume a loss of 500 which includes both optical and mode-mismatch losses discussed below. The corresponding loss in the aLIGO detectors is estimated to be roughly 10 times larger.
